Very little is known of the possible long-term biological effects of habitual marijuana smoking. We will therefore continue our program on the responses of the lung and its defensive system to marijuana smoke. The established in vivo exposure system will be extended for chronic periods of smoking and the subsequent effects on the biochemistry, morphology and function of the lung and the pulmonary alveolar macrophage will be measured. In vitro methods will also be used to help isolate those components in the smoke which specifically affect alveolar macrophage bactericidal function. Quantitative light and electron microscopy will be used to clarify group and individual differences in response.